The present invention relates to conveyors, detection and measurement of wear in machines having relatively rotating housings and parts such as radially extending blades subject to wear which may exceed a critical degree, and in particlar to scroll type conveyors in which one or more helical blades are carried by a shaft or the like and at least partially encased in a housing.
In order to convey a substance toward one end of the housing, the blade or blades may be rotated within the housing, or the housing may rotate about the blades, or the housing and blades may both rotate at different speeds so that there is relative rotative movement between the blade or blades and the housing.
The outermost edges of the blades of such conveyors wear with use, and while it is desirable to periodically check the degree of wear, this has hitherto necessitated the troublesome, time consuming, and sometimes inaccurate procedure of at least partially disassembling the machine and visually inspecting the blade. The present invention provides a measuring device which may be inserted into an aperture in the conveyor housing to measure the distance between the outer edge of the blade and a fixed reference point. A plug is used to stop the aperture when the conveyor is in operation.
Blade wear can thus be measured by stopping the machine, removing the plug, clearing a path through the adjacent bed of sediment, aligning the blade edge with the aperture, and inserting and operating the measuring device.
In some types of conveyors it might be possible to have a measuring device permanently mounted in the housing wall.
It is, therefore, an object of the present invention to provide a means and method of measuring wear of a conveyor blade while retaining the conveyor in assembled condition.
Such conveyors often have blade wear characteristics which vary along their lengths. A blade may exhibit considerable blade wear along a portion of high wear characteristics while the wear at a second portion of the same blade having low wear characteristics may be so slight as to be very difficult to measure. Yet this second portion of the blade may be of critical conveyance capacity, i.e. slight wear along this second portion may considerably reduce the connveyance capacity of the conveyor as a whole. The present inventor has found that, while wear and conveyance capacity vary along a blade's length, the wear at a first portion of the blade is usually related, so as to be indicative of, the wear and conveyance capacity of other portions. For instance, the wear at various portions may be mathematical functions of the wear at the first portion. If the measuring device of the invention is located adjacent a first portion of the blade, the measurement obtained there can be used to determine the wear at other portions. Preferably the measurement is taken at a first portion of high (and therefore easily measured) wear characteristics, and used to determine or predetermine the wear and/or conveyance capacity at a second, less easily measured portion.
It is therefore a further object of the present invention to provide a means and method for measuring wear at a first portion of a conveyor blade to determine wear and conveyance capacity at a second portion of the blade which may be less readily measurable.
A preferred embodiment of the invention includes a plurality of apertures in the conveyor housing for receiving a plurality of measuring devices. These apertures are equally spaced circumferentially of the housing at a predetermined location along its lengths. This arrangement maintains the balance which is needed, e.g. in centrifuges or other devices in which the housing rotates, and which might be disturbed by the use of a single aperture. In the case of a single blade conveyor, the provision of two or more apertures in the housing reduces the amount of rotation needed to align the blade edge with an aperture. In the case of a multiple lead blade, i.e. a plurality of parallel helical blades arranged about the same shaft, the number of apertures and measuring devices provided is preferably equal to the number of blades. Then when one blade edge is aligned with one aperture, the edges of the remaining blades will be aligned with the other apertures so that all the blades can be checked with the machine in a single position.
It is therefore a further object of the present invention to provide a plurality of measuring devices equispaced about a conveyor housing at a given location along the length of said housing.